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    Help i dont understand how water moves up the xylem.
    Quote me if you reply thanks.
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    (Original post by Mally-xo)
    ummm they are about 30 pages and they have pictures/diagrams that I did on Paint as well!
    I will attempt to put them up tomorrow okay? I have to go babysitting now, joy
    Can you email me the notes please?
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    Past papers anyone?
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    (Original post by Silly-samz)
    Can you email me the notes please?
    sure, private message me your email
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    you'll be fine
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    (Original post by Rosi M)
    Hey can anyone give me the link for the mark scheme for Tuesday 8TH JUNE 2008 TRANSPORT LEGACY paper? I would really appreciate it. Thanks
    go on paper bank
    have anti-virus software though
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    (Original post by 000015080)
    Help i dont understand how water moves up the xylem.
    Quote me if you reply thanks.
    Hey.. water moves up the xylem in 3 ways

    1) Root pressure/Hydrostatic pressure:
    As the minerals are ACTIVELY transported into the xylem vessel, this lowers the water potential of the xylem vessel causing water from the endodermis cells to move down the water potential gradient and enter the xylem by osmosis. This increases the root pressure/hydrostatic pressure. At the top of the plant, water is lost by transpiration so the hydrostatic pressure at the top is low. Water then moves down its hydrostatic pressure gradient UP the xylem vessel.

    2) Transpiration pull/stream
    Water is lost from the aerial parts of the plants by transpiration. This loss of water must be replaced by water coming up the xylem. Water molecules are attracted to each other by cohesion. The cohesive forces are strong enough to hold the molecules in a long chain/column. As water is lost from the top in a chain, this puts tension in the xylem vessel. This ensures that water moves up the xylem as a long chain/column

    3) Capillary action
    Water molecules are also attracted to the walls of the xylem vessel. This is called Adhesion. The adhesive forces are strong between the water and xylem 'cos the xylem is narrow. This attraction also allows water to flow up the xylem vessel

    Thats all Hope that helped. Its good revision for me too x
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    (Original post by Deyn_08)
    go on paper bank
    have anti-virus software though
    Yep thanks!
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    (Original post by pastpaper-guy)
    i bet theres going to be a 5 marker on setting up a potometer.
    Setting up potometer? How do you set it up.. can you explain please?

    The books very vague on the potometer stuff. I had to learn the precautions from a mark scheme! There's 5/6 mark questions on precautions and the book has literally 2/3 words (no air bubbles or something)
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    (Original post by pastpaper-guy)
    i bet theres going to be a 5 marker on setting up a potometer.
    lmao i hope not!
    i was doing the specimen paper and literally, they gave 2 whole pages and 7 marks on a question asking how to set up a potometer :| i was just like, are you kidding me? i wrote like 5 lines and still managed to get 5 marks lol dunno why they gave 1 and half pages for the other 2 marks :|
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    (Original post by CullenLoverX)
    lmao i hope not!
    i was doing the specimen paper and literally, they gave 2 whole pages and 7 marks on a question asking how to set up a potometer :| i was just like, are you kidding me? i wrote like 5 lines and still managed to get 5 marks lol dunno why they gave 1 and half pages for the other 2 marks :|
    Lol can you please explain how to set up a potometer and any other necessary information? please?! :confused:
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    (Original post by Rosi M)
    Lol can you please explain how to set up a potometer and any other necessary information? please?! :confused:
    Lol well this was in the mark scheme

    1 cut (healthy) shoot under water (to stop air entering xylem vessels);
    2 cut shoot at a slant (to increase surface area);
    3 check apparatus is full of water / is air bubble free / no air locks;
    4 insert shoot into apparatus under water / AW;
    5 remove potometer from water and ensure , airtight / watertight, joints around shoot;
    6 dry leaves / AW;
    7 keep , condition(s) / named condition(s) , constant;
    8 allow time for shoot to acclimatise / AW;
    9 shut screw clip;
    10 keep ruler fixed and record position of air bubble on scale;
    R ‘move bubble to end’ ideas
    11 start timing and, measure / calculate, distance moved per unit time
    / AW;

    hope that helped.

    i probably won't remember that though lol :P

    but seriously, what good will it do us knowing how to set up a potometer?? like, i don't really see how knowing that will be beneficial to my future :confused:
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    (Original post by fahimak)
    hey can anyone explain fetal haemoglobin 2 me plz???
    still dont understand it :confused:

    I was very confused with this last year (i'm resiting F211 this January). Sods law it came up in june 2010 with this question: "Explain why the curve for fetal oxyhaemoglobin is to the left of the curve for adult oxyhaemoglobin"

    So good news for this January is it's VERY unlikely to come up in the paper. So i wouldn't worry too much about it
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    Anyone have any predictions for the exam on TUESDAY (eeek)?
    I'm thinking full details of mitosis, heart valves (atrioventicular/semi lumar), mechanism of transport in phloem, transpiration...

    i'm hoping nothing on homologous chromosomes, budding, Bohr shift and fetal haemoglobin...but these came up in June 2010 so tis unlikely
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    (Original post by LisaWilliams)
    I was very confused with this last year (i'm resiting F211 this January). Sods law it came up in june 2010 with this question: "Explain why the curve for fetal oxyhaemoglobin is to the left of the curve for adult oxyhaemoglobin"

    So good news for this January is it's VERY unlikely to come up in the paper. So i wouldn't worry too much about it
    What do you reckon is coming in the paper.. any ideas?
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    (Original post by LisaWilliams)
    Anyone have any predictions for the exam on TUESDAY (eeek)?
    I'm thinking full details of mitosis, heart valves (atrioventicular/semi lumar), mechanism of transport in phloem, transpiration...

    i'm hoping nothing on homologous chromosomes, budding, Bohr shift and fetal haemoglobin...but these came up in June 2010 so tis unlikely
    haha you just answered the question!
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    (Original post by pastpaper-guy)
    i bet theres going to be a 5 marker on setting up a potometer.
    Hmm you could be right. There was a question in January 2010, but this was about precautions (being airtight/no bubbles etc) Do we actually have to know how to set it up? I have no clue about that :P
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    (Original post by CullenLoverX)
    Lol well this was in the mark scheme

    1 cut (healthy) shoot under water (to stop air entering xylem vessels);
    2 cut shoot at a slant (to increase surface area);
    3 check apparatus is full of water / is air bubble free / no air locks;
    4 insert shoot into apparatus under water / AW;
    5 remove potometer from water and ensure , airtight / watertight, joints around shoot;
    6 dry leaves / AW;
    7 keep , condition(s) / named condition(s) , constant;
    8 allow time for shoot to acclimatise / AW;
    9 shut screw clip;
    10 keep ruler fixed and record position of air bubble on scale;
    R ‘move bubble to end’ ideas
    11 start timing and, measure / calculate, distance moved per unit time
    / AW;

    hope that helped.

    i probably won't remember that though lol :P

    but seriously, what good will it do us knowing how to set up a potometer?? like, i don't really see how knowing that will be beneficial to my future :confused:
    Thanks! Thats really similiar to the precautions which I learnt from mark scheme as the book is useless on the potometer! Oh i give up!! Haha yeah your right.. I think the same about half the syllabus!
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    (Original post by Rosi M)
    haha you just answered the question!
    I have spent the whole of today sieving through the F211 past papers! I should just not be lazy and revise the whole specification so i'm ready for anything, oh well :P
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    (Original post by Rosi M)
    Hey.. water moves up the xylem in 3 ways

    1) Root pressure/Hydrostatic pressure:
    As the minerals are ACTIVELY transported into the xylem vessel, this lowers the water potential of the xylem vessel causing water from the endodermis cells to move down the water potential gradient and enter the xylem by osmosis. This increases the root pressure/hydrostatic pressure. At the top of the plant, water is lost by transpiration so the hydrostatic pressure at the top is low. Water then moves down its hydrostatic pressure gradient UP the xylem vessel.

    2) Transpiration pull/stream
    Water is lost from the aerial parts of the plants by transpiration. This loss of water must be replaced by water coming up the xylem. Water molecules are attracted to each other by cohesion. The cohesive forces are strong enough to hold the molecules in a long chain/column. As water is lost from the top in a chain, this puts tension in the xylem vessel. This ensures that water moves up the xylem as a long chain/column

    3) Capillary action
    Water molecules are also attracted to the walls of the xylem vessel. This is called Adhesion. The adhesive forces are strong between the water and xylem 'cos the xylem is narrow. This attraction also allows water to flow up the xylem vessel

    Thats all Hope that helped. Its good revision for me too x
    Thanks x
 
 
 
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